#region Apache License
//
// Licensed to the Apache Software Foundation (ASF) under one or more 
// contributor license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright ownership. 
// The ASF licenses this file to you under the Apache License, Version 2.0
// (the "License"); you may not use this file except in compliance with 
// the License. You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
#endregion

using System;
#if NETCF
using System.Collections;
#endif

namespace log4net.Util
{
  /// <summary>
  /// Implementation of Properties collection for the <see cref="log4net.ThreadContext"/>
  /// </summary>
  /// <remarks>
  /// <para>
  /// Class implements a collection of properties that is specific to each thread.
  /// The class is not synchronized as each thread has its own <see cref="PropertiesDictionary"/>.
  /// </para>
  /// </remarks>
  /// <author>Nicko Cadell</author>
  public sealed class ThreadContextProperties : ContextPropertiesBase
  {
    #region Private Instance Fields

#if NETCF
    /// <summary>
    /// The thread local data slot to use to store a PropertiesDictionary.
    /// </summary>
    private readonly static LocalDataStoreSlot s_threadLocalSlot = System.Threading.Thread.AllocateDataSlot();
#else
    /// <summary>
    /// Each thread will automatically have its instance.
    /// </summary>
    [ThreadStatic]
    private static PropertiesDictionary _dictionary;
#endif

    #endregion Private Instance Fields

    #region Public Instance Constructors

    /// <summary>
    /// Internal constructor
    /// </summary>
    /// <remarks>
    /// <para>
    /// Initializes a new instance of the <see cref="ThreadContextProperties" /> class.
    /// </para>
    /// </remarks>
    internal ThreadContextProperties()
    {
    }

    #endregion Public Instance Constructors

    #region Public Instance Properties

    /// <summary>
    /// Gets or sets the value of a property
    /// </summary>
    /// <value>
    /// The value for the property with the specified key
    /// </value>
    /// <remarks>
    /// <para>
    /// Gets or sets the value of a property
    /// </para>
    /// </remarks>
    public override object this[string key]
    {
      get
      {
#if NETCF
        PropertiesDictionary _dictionary = GetProperties(false);
#endif
        if (_dictionary != null)
        {
          return _dictionary[key];
        }
        return null;
      }
      set
      {
        GetProperties(true)[key] = value;
      }
    }

    #endregion Public Instance Properties

    #region Public Instance Methods

    /// <summary>
    /// Remove a property
    /// </summary>
    /// <param name="key">the key for the entry to remove</param>
    /// <remarks>
    /// <para>
    /// Remove a property
    /// </para>
    /// </remarks>
    public void Remove(string key)
    {
#if NETCF
      PropertiesDictionary _dictionary = GetProperties(false);
#endif
      if (_dictionary != null)
      {
        _dictionary.Remove(key);
      }
    }

    /// <summary>
    /// Get the keys stored in the properties.
    /// </summary>
    /// <para>
    /// Gets the keys stored in the properties.
    /// </para>
    /// <returns>a set of the defined keys</returns>
    public string[] GetKeys()
    {
#if NETCF
      PropertiesDictionary _dictionary = GetProperties(false);
#endif
      if (_dictionary != null)
      {
        return _dictionary.GetKeys();
      }
      return null;
    }

    /// <summary>
    /// Clear all properties
    /// </summary>
    /// <remarks>
    /// <para>
    /// Clear all properties
    /// </para>
    /// </remarks>
    public void Clear()
    {
#if NETCF
      PropertiesDictionary _dictionary = GetProperties(false);
#endif
      if (_dictionary != null)
      {
        _dictionary.Clear();
      }
    }

    #endregion Public Instance Methods

    #region Internal Instance Methods

    /// <summary>
    /// Get the <c>PropertiesDictionary</c> for this thread.
    /// </summary>
    /// <param name="create">create the dictionary if it does not exist, otherwise return null if does not exist</param>
    /// <returns>the properties for this thread</returns>
    /// <remarks>
    /// <para>
    /// The collection returned is only to be used on the calling thread. If the
    /// caller needs to share the collection between different threads then the 
    /// caller must clone the collection before doing so.
    /// </para>
    /// </remarks>
    internal PropertiesDictionary GetProperties(bool create)
    {
#if NETCF
      PropertiesDictionary _dictionary = (PropertiesDictionary)System.Threading.Thread.GetData(s_threadLocalSlot);
#endif
      if (_dictionary == null && create)
      {
        _dictionary = new PropertiesDictionary();
#if NETCF
        System.Threading.Thread.SetData(s_threadLocalSlot, _dictionary);
#endif
      }
      return _dictionary;
    }

    #endregion Internal Instance Methods
  }
}

